Apparatus for separating liquids of different specific gravities



`lrune 2, 1942. -J,. HlRsHs-rElN APPARATUS PoR SEPARTING' LIQUIDs OPvDI'PPEJVENT SPECIFIC GRAVITIES YFiled oct. 4, 1958 2 Sheets-Sheet l J nIlI Inu llll/ A j INVENTOR. Jeff/H Mash/575m# BY @@Qyf/Mw ATTORNEYg June2, 1942.` J. HSHSTEN 2 2,284,737

APPARATUS FORV SEPARATING LIQUIDS OF DIFFERENT SPECIFIC GRAVITIES Filedoct. 4, 193e 2 sheets-sheet 2 ATTQRNEYS Patented June 2,

; man: STATES PATENT' 1l-FICE APP i f a meer AitArUsFon sarAnA'rrNGLroums or ,n i

nrFFanENfr. SPECIFIC Gltavx'rms 1 "Joseph nirei'stei) simieiir'eighte,dh'ie, assimand `liiildrecl Hirshsteim por lto Ruth Newman napisiieatiosoetebee 4.11933, serai Nazsaazs L" somma '(cLz'ioLL-sciflThe general ,objectV of the `present i invention is the provision/ofarnethod olifseparating` and resideration to the diiiiculties andineiiiciencies cre-i` covering greaseJoils and `fat'frorn wastewaters zin an eilcient mannerundercontinuous flowcon dimens of the waste water.n g l A further objectfof my invention is 'the provision of `an efcientmethod of `recovering grease,

oil and-fat froniwaste watersunder intermittent ilow conditionslofthewastewateri A` further object'of' m3/"inv, ntioni is thepro-` visioniof, a grease,` oil` andiat-recoveringA ap-v` paratus, into whichwastewaters carrying grease,`

oil or fat and solids "may enter under continuous flow conditions,andout` of which the" wastewa- I ters and solids may flow `under suchcontinuous flow" conditions,'while greasdffoil or fat maybe removedtherefrom n continuously and be discharged-from the apparatusautomatically, all

of which is effected inahighly etlicient manner. f "A still further4object of finyuinvention is the* `provision of an"oil,fgreaseand fatseparator` which win intermittently ,ninetiesH to* `discharge grease,oils orffat recovered-hom "waste waters upon 4the entrance of grease;`oil orfat-laden wastewater'tli'ereintoiV `A still further 'object ofthefpresent invention is the provisionoi anovelmethod of utilizing thelaction 'of flowing waste waterste separate oils, greaseorffatftherefrom"andneiiect a complete separation of the `recoveredgrease, oilsand `fats from the influenceyof ithe wastewaters.`

, stili ieneiher objectief my inventien is to eecomplishuthe `foregoing'objects in a separator apparatus which'will be` extremely` simple inits construction and parts; andwhich, in its functions,

wiiijidepexid entirely Aupmf `cennfeiiea new and pressure actions off-1the waste waters being charged into the same.y

` A variety of; grease traps or grease separators heretofore has been"proposed. and a number lof various constructions thereoilhave from tirneto timebeenplaced in` use, all of which eitheruexn-r `bodied orcontemplated the discharge of grease,-

oil or fat-"laden: wastewater `into a container or receptacle,V "wherein31 the lighter gravity contents of thevwaste waterbecame separatedtherefrom as the waste water passed throughthe receptacle andwasdischarged to a sewer connection, to-

i gather `,with [any solids which may: have had a tendenc'y'to settletothe bottonro! the receptacle. Likewise, oil, grease and' i atseparators. of 'the type above referred to, have been proposed,.wherefin some form of grease, oil or iat-removing means or skimmermeans lwas incc'irporatedfiny the sepf n insofar as the applicant hasarator apparatus;`

\ oilseparator, wherein waste waters may be dis-` knowledge, no one'hasever given serious conated bythe wide variations of the so-called normalwater level of the trap or separator. This'socalled'normal water levelis supposed to `beden termined by theoutlet level o! the apparatus, but

varies` under varyingoperating conditions, dueto the accumulation ofrecovered oilsg'grease or iat within the separator apparatus, and suchaccumuf `.lation frequently results in the discharge of the recoveredmatter into the sewer line. Also; such accumulation frequently resultsin a short circuiting of the grease-laden waste waters directly from theinlet to the outlet of the apparatus. This variatidn of water level:within theseparator isf considerably increased by compression of airwithin the upper region of the separator receptacle when the same is notequipped with a vent stack or other venting means. i

By mylpresent invention I utilize a Vgrease or charged continuouslythereinto and impact a substantial i body of water present within theseparatorfcomprising a residue of previously discharged waste water, andthrough which the discharging waste `water can pass and flow out of the,separator, so long as there isan inilow of waste water `to theseparator. To this extent the ap-` par tus" shown is l. common to priorpractices. How ver, in` such an apparatus, I utilize amethod ofcontrolling the localized rates of ilow and the directions of flow ofthe incoming wastewater in such a manner that` a body of water alwayspresent `in the separator receptacle, is controlled, whereby asubstantial portion thereof is maintained in a non-turbulent conditionand the turbulence created by the intlowing waste water i is confined toanother zone of the body of water in the withinthe receptacle, forthepurposes and manner hereinafter described.- i

- Fromthe inflowing waste water I separate two relatively thinxstreams.`One stream is utilized to sweep all solids settling to the bottom ofthe separator receptacle to the outletend thereof,

whereby the solids maybe constantly discharged and thereby prevent`clogging of the apparatus. The other stream is directed upwardly to anupper stratum ofl separated grease. `oil or fatiioating upon-theturbulent portion of the body of water within the separator, `whereby asubstantial i `part of `this grease, oil for -fat may be skimmed,

flowed or removedftherefrom to a region within the receptacle locatedabove a relatively nonturbulent portionv of the body of water withintheseparatonthus increasingto a considerable extent, the thickness ordepth of the recovered material. This localizing of the fats only takesplace during those periods when the contents of the separator are beingsubjected to inflow and outflow influences of the waste water passingthrough the separator. A main stream is controlled to create turbulenceand facilitate the separation of the grease. l

When closed grease separators of the general type, herelnbefore referredto, are operating under waste water iiow conditions, the height of thelevel of the grease, as well as the height of the along the line 4 4 offragmentary cross-sectional views, illustrating various water and greaselevels of the separator apparatus.

Substantially all of the elements of the apparatus are shown in-Flgs. 1and 2. The liquidseparating part of the apparatus comprises arectangularly shaped basin I 0, and a grease, oil or fat receptacle Ilwhich may be incorporated in the separator receptacle I0, if desired, ormay comprise, as shown, a separate container conlnected to thereceptacle I in a suitable manner,

level of the water within the receptacle, is increased to a considerableextent, even though the space above`the grease in the closed receptacleis vented. However, this variation in the water and grease levels can becontrolled, to some extent, by proper venting By increasing the depth ofthe layer of floating grease, oil or fat upon the body of the waterwithin the separator dur'- ing-waste water inflow operation, at alocalized zone within the receptacle of the separator, I find that it is.possible to drain out of the receptacle intermittently, a certainamountof grease without draining waterlby locating the grease passagewayoropening at a proper elevation relative to the localizedzoneofgreaseaccumulation, and the normal outlet ywater level. A 'l l Ihave'determined thatI can incorporate in a.`

grease separator apparatus of proper dimensions to meet practicalplumbing installation requirements', a means for carrying outtheforegoing described method of separating and recovering encounteredbythe settling of solids to the ,bot-.

tom of-the separator receptacle withsubsequent clogging of the outlet,despite the fact that I have greatly decreased the angle` of-slopeofthebottom 'of the `separator receptacle and v/have prac tically eliminatedconvergence: of the sidewalls thereof, anA arrangement heretoforeconsidered essentialv to the successful 'i evacuating f of solids from`grease and oil separators of the general type to which this application`refers.

stated-,w I-. accomplishA the foregoing underA waste waterilowconditions, and a localized col.-`A

umn of recovered grease, oil or fat of a substantialzheightisaccumulated, and -due ,to the. gen-v eral upward surge .created in theseparator .ref-

ceptacle vunderxwaste water -ilow conditions, a part of the recoveredgrease, oils vand fat can be drained outof the receptacleupon eachopera-l tion thereof, without anyxdanger of the waste` water levelrising to thexgrease drain outlet, even under .a maximum gallon lperhour 1 waste water discharge-condition. l. A f

VIn the drawings, in Fig'.vv 1

rectangularly shaped basinaand this gure'comprisega `cross-sectionalelevation, vtaken longitudinally and centrally of the basin structure;Fig. 2 is a plan view of the apparatus, part of which is'shownincross-section, taken substan- I'show agrease, oill and fat-recoveringapparatus in the form' of a.

as illustrated in Fig..-2.

As illustrated, the receptacle III has a substantial depth relative tothe width and length thereof, the dimensioning being dependent upon theilow rate inv gallons per hour of the waste water which is to passtherethrough. 'I'he receptacle III has an inlet branch I4, and an outletbranch l 5 formed at substantially the same level andare located atsubstantial elevations above the bottom of the receptacle. Piping I6extends to the fixture or device being serviced by the apparatus fromthe inlet branch I4, and piping I1 joined to the outletbranch I5vconnects the outlet end of the apparatus to a sewer or other drainagesource. 'I'he receptacle I0 is provided with a cover 20, securedato thereceptacle body by any convenient means, such as screw members 2|, therebeing agasket 22 interposed between the receptacle body and thecover,whereby the apparatus may be sealed atmospherically.

The grease receptacle Il is similarly provided with a removable lid 24,which is clamped in airtight relation to vthe grease receptacle II byconvenient securing means, such as screw members25.- The outlet branchI5 o f the apparatus is formed on a vertically extending outlet conduitleg 21, whichextends to the top wall of the receptacle, at which placethe apparatus is provided with a clean-,out opening sealed by aremovable screw plug 28. An opening is also provided at the bottom ofthe outlet part of the tially alongV the line 2-2 in Fig. 1; Fig. 3 -isa elevational viewof one ofthe elements comprising the apparatus; `andas vviewed substantially apparatus, which is closed by a removable plug29.

The receptacle I0 has an outlet opening generally indicated by thereference numeral 30, extending substantially from'side wall to sidewall thereof, and along thebottom of thereceptacle. Converging walls 3|and 32 (see Fig. 2) have top and bottom wall sections and constrict theoutlet conduit to substantially the diameter of the upright outlet leg2l. It should be noted that the convergence of the walls 3l and 32,guiding the outilowing waste water to the outlet leg 2l, will cause anincrease in velocity of the flowing water and vthus effects the ejectingof the solids as the waste water flows upwardly and out o f the outletof the grease receptacle. It jwill be obvious that the position of theoutlet branch I5 will determine, in a. general way, the amount of liquidretained in the receptacle I0, when the apparatus is not in operation.

The bottom of the receptacle I0 is shown as sloping slightly from theinlet en d wall of the receptacle toward the outlet 30, and this bottommay or may not betprovided with a centrally located channel formation(indicated by the referencenumeral 3l, in Fig. 3),y for the purpose ofassisting the flowing waste water in shifting solids toward the outlet30, shouldl there be any solids settling to the bottom of the receptacleduring the owing operation.

.The control .of the flowing waste water within the receptacle, andtheaccumulated or recovered Fig, 1; Figs. 5, 6 and l are `the lower end foril; seeFig.

floating grease, oils or iat, is effected .by the dimensioning. and`positioning of a partitioning two minor' streams"`an`d a major stream.`Thus,

a. partitioning wall 40 extends across the receptacle, transversely `olfthe direction of ilow of the Wastewater through thereceptacle and servesto confine the` activities of the maior `stream. in

vIt will be noted that or zone-or the receptacle? s c s the wall 40terminates slightly above theupper c s andextends a substantial.distance above the center line of Ythe-inlet and outlet branches I4and- I5, respctively.` The partitioning wall 4|l` is spaced closertothecoutlet` end of the receptacle thanto the inlet'end, and dividesthe`interior of the receptacle into substantially' twomain zones,

f one comprising `the turbulent zone T, and the other al, zone which Idesignate a quiescent zone c Q. The upper portion` of the partition wan4u" what 1 ohoseto can` o turbmentoomnartment "1s 1 edge o! the outletopening 3|),

A fifth baule Itis disposed adjacent the bot-,-

tom of the receptacle Ill, intermediate the partition wall 40,` and` thefourth baille member 41 and extends upwardly from said bottom a`sufilcient distance to deflect upwardlyinto the turbulent zone T, apart of the waste water which has own beneath the baille 41, thusserving to cause an upward pressure in the turbulence zone. The bottomedge of the ilfth baille 50 'is provided with downwardly-extendinglugsin the manner `of the construction of the bottom `oi! the'baiile member41, whereby the shallow stream of waste wateris permitted to flowtherebeneath along the bottom `of the interceptor toward the outletopening 30 thereof." c l A minor streamof the waste water, of a shallowdepth, ilows directly along thexbottom of thereceptacle I0 having astream width extending from side wall to side wall thereof toward theoutlet'opening 30. The4 other `4minor stream is directed upwardlybetween the bailles y43 and 45,

while the main volume oi incoming waste water is directed intotheturbulent zone T, wherein sumclent agitation is imparted thereto tocause is provided `with a`plurality'o`i jet slots 4I, the

purpose of which willbedescrlbed hereinafter.

Adjacent the inlet end of the 1 receptacle, I

provide a main deflecting baille 43, ywhich extends vertically above andbelow the entire area of the inletope'ning, andserves tofdirect theiniiowing waste water downwardly toward `the bottom wall o! thereceptaclaf However, this baille 43 has the loweredge thereofposltionedasubstantial distance abovethe bottom `of the receptacle.`'The baille 4,3` serves to break up the pressure of the inilowing wastewater 4and toddecrease surge movements that accompany the flushing oiwater in theplpe' i3, and is of sumcient height `to prevent theinilowing jwaterffrom ilowing over its top;` `adjacent to thebafneylla,"anajin `pamamol relation therewith,I provide a second baille memberV.44, which extends downwardly a` substantial distancebelowthelower edgeto!" the banle memberv 43, but .does not extend to the bottom wall of lthe receptacle.1 The baille serves the purpose of directing a minor partof the inflowing waste water upwardly, which directed lwasta water willflow upwardly between theflrst baille 43 and a thirdbailie member 45..The baille 44 alsos'erves the particles of iat, grease or oil toseparate from`the water and rise to the top surface ofthe water `in theturbulent zone T. The minorv stream directed upwardly between thebaiiles 43` and 45 flows through the jet slots 46 in a horizontal`direction against the ylayer of accumulating grease, oil or fat atthetopZ of the turbulent zone T, causing the same to be forced towardthe outlet end wall 5| of the receptacle through waste water in the zoneQ. A continuous flow of waste waterithroughthe inlet and outlet will theslotted openings 4l formed in the top portion Yof the partition wall 40,thereby causing an increase in the deptho! the fats, greases or oilsaccumulated on the top surface of the quiescent cause the normal waterlevel in both zones Tand i 'Q to be raised during the period the wastewaters ,are passing through the device, thereby assisting the flow ofgrease, oils or fats from zone T to zone Q. o

To remove the recovered grease, a draw-ofi opening 52 `is shown close tothe end wall 5l thereof, at a suicient `elevation to permit the upperpartof the built-up column of grease` to to guide the' main stream 'ofinilowing wastef water downwardly as itleaves the bottom fedge of baille43. 'I'he baille membersghas the lower t 4 end-thereof terminatingabovetheupper edge of the baille member 44 and is provided with a series' o!jet slots 46, for a purpose stated here- 3i The baffles servesfto-directthe bafile. 41 is arranged adjacentfto ,-andl parallelism with` thei'fhree'` `bellies 'above described, with the -bottomedge thereof `injuxtaposition to the bottom wall of the receptacle waldiyltotheturbaienoezone "1".'` `teme n is provided with downwardly extendingVrest lugs 4I, wherebyabottom wallow space 43y is a!- ,iordedsbstantiallv-theentire width oi the ref ceptacle foidirectdow off `thewastewater, along i `the bottoms of` the receptacle; `the now `being inthe form oi L bottomorthe receptacle towardthe outlet openiingjil...fl'hen baille 4111s also provided ,with afcentral, downwarclly`extending portion33, which intothe troughof the channel,`

wherebyi'ull capacity of the ychannel is`decreased`.

a broad, shallow. stream across the escape 'into the `closed greasereceptacle II.v A connection 52 extending between the two receptaclesguides the drawn-oft grease tothe receptaclev I I. The elevation o!opening 52 should be adjustable, relative to the outlet and passageway.aswill be explained. A suitable means of adjustment may comprise thethreaded eccentric rings Maand B2b.'

'I'he location of the draw-oil opening 52 relative to the normal waterlevel of the waste water in the outlet leg 211s important in that thegeneral average of water displacement within `the `receptacle by theweight of the grease is such thatl approximately nine-tenths of theheight of the layer of grease willv be disposed below the normal `waterlevel o! thewaste waters within the leg 21 when the device is not inoperation;

inthe zone AQ will be raised above said lowermost part oi'opening12. Thedepth or thickness of' the layer of grease when the device isnot inoperation is ldeterminedby the height of thebot'toms s of the slots A46in the partition wally I0, above the normal water level in the outletleg 21. However,

Toprevent the compression of air in the upper i part of the receptacle I0, due to the rise of the water and grease levels therein causedlby inflowing waste waters, I provide a narrow release passageway 55. Thispassageway may be suitably formed inthe receptacle structure to extendfrom adjacent the top region of the receptacle I downwardly and into theupright outlet leg 21 at a'point' which is below the outlet branch I5,to therebyrobtain a waterl seal when the separator is not.: inoperation. Also, it wil be noted that thegrease-draw-oil opening 52 islocated at such eevation thatthe air-releasepassageway 55 also serves tovent the grease receptacle I I to the outlet ofthe apparatus, while atthe same time the entire apparatus can be maintained. in a sewer gastrapped condition.

In Figs. 5, 6 and '1 I have more or less diagrammatically illustrateddifferent static conditions of the apparatus at different periods. InFig. the apparatus is illustrated to show the relation of the normalwater level within the receptacle I0 to the inletand outlet and to thejet slotsIB formed in the baille member 45, and the jet slots" 4I,formed in the partition wall 40. In Fig. 6 I have illustrated the staticcondition which prevails when some grease, oil or fat-laden waste waterhas passed through the device, showing a layer of the separated materialoating upon the topfof the waste water in the quiescent zone Q, which isthicker than the layer floating upon It will be apparent from theforegoing that' apart from the high efficiency in fat recovery, whichf'Iobtainby the particular arrangement of the baffles, partition wall andthe always present,` substantial body' of quiescent waste water withinthe receptacle I0, I alsoobtain an automatic skimming effect ofaccumulated grease,

f oil or fat within the apparatus, part of which can be drawn off uponeach operation thereof.

` One of the great advantages in thus automatically obtaining thisskimming action is that the yuse of mechanical contrivances, such asfloats,

valves, gates, etc., are eliminated. Furthermore,

the normal static water level within the receptacle I0. can bepredetermined fairly definitely, and can be maintained and the loweringof such static normal water level by accumulated grease and fat, byover-accumulation thereo'.. .vithin the separator I0, with subsequentevacuation of the greases, oils and fats into the sewer lines, isprevented.

`The intimate location of the plurality of vertically extending bafflesrelative to the receptacle inlet and to each other, together with thepresence at all times of a substantial body of waste water therein, allserve tol greatly decrease the the top of the quiescent water in theturbulent t zone T. In Fig. 7 I have illustrated the relation of thewater level in thetwo zones T and Q, to the water levelv in the outletleg 21, the water level in the latter being always determined Vby thelowermost point of the outlet branch opening I5. In Fig. 'ltheaccumulated separated grease is shown to be of such thickness thatthetop level.V thereof is about at thebottorn of the slots 4I, formed inthe partition wall 40'.

In Fig. 1 the operation of the apparatus under waste water flowconditions is illustrated insofar as the influence of -the controlledstreams of inflowing waste waters are concerned. The flowing control andactions of the streams are illustrated by arrows and it will be notedthat the upper surface `of the grease in both zones is raisedconsiderably above the level of the outflowing waste water in the outletbranch I5. The

column of grease in the quiescent zone Q has been built downwardly todepress the. water level in this zone relative tothe water level in theturbulent zone and the entire body of waste water and grease layerswithin the receptacle have beentelevated considerably by the pressure ofthe. inflowing waste water, whereby the upper surface of the built-upgrease column in the quiescent zone Q is forced Vabove thel bottom ofthe grease draw-off out1et52, thus causing grease ,to flow out of thereceptacle Ill.

The system of bailling described creates a con`` grease from the underside of the floating .layer thereof. Tests have shown that the onlygrease lost comprises the part thereof which becomes highly emulsitled.

voils or fats contained in water.

velocity of' the inflowing waste waters, thus lincreasing, to aconsiderable extent, the fat, grease or oil recovery efliciency of thedevice. It is to be understood that the position of the inlet y branchI4 may be raised or lowered with a corv responding shift in itsassociated baiiles without depreciating the efiiciency of the device.Also it is to be understood that while the general shape of theseparator receptacle is illustrated as being rectangular, the inventionmay be prac ticed with receptacles of other shapes and that theinventionmay be employed for the separation of liquids of differentspecific gravities, other than waste waters carrying greases, oils orfats.

All of the foregoing stated desired results are obtained by the methodand apparatus disclosed, without in any way decreasing the constantsolids evacuating etliciency of the device, for

even though the shape of the separator recepta cle is shown as beingrectangular, with a bottom wall sloping only slightly to the outletopening, nevertheless `experience has shown that solids do notaccumulate in the bottom corners of the receptacle.

I claim:

1. A grease, oil and fat-retrieving device, of the air-.cooled ltypeadapted to function under continuous flow condition, comprising areceptacle having an inlet branch and an outletA of, to divide thereceptable into two zones, in

one of which turbulence in the Waste water flowing into the receptacleis created, and in the otherl ofl which the waste Water is relativelyquiescent, and baffling means disposed adjacent the inlet opening of thereceptacle serving to divide inflowing waste waters into two auxiliarystreams and a main stream, said baffling means serving to direct one ofthe auxiliary streams being directed toward the outlet immediately adja-A,cent the bottom of the receptacle, and the other auxiliary streamupwardly and then horizontally against separated grease, oils or fats,andthe main stream into said turbulent zone of the receptacle to thereineffect 'separation of grease, the inflowing waste 2. A grease, oil andfat separator, comprising a the top of the receptacle and terminatingabove the inlet opening and extending downwardly within the receptacleandterminating above the N outlet opening, said partition wall beingdisposed nearer to the outlet end of the receptacle than rect a part ofthe infiowing waste waters into the turbulence zone and a second baillemember positioned to intercept said last named inilowing to the inletend thereof and `having openings formed in the top portion thereof topermit oil, grease or fat to pass from one side of the partition to theother side thereof, and. baffling `means disposed adjacent the inletopening ofthe receptacle for diverting and directing upwardly a part ofthe incoming fluid entering the receptacle, said baiiiing meansincluding a partition provided with openings formed adjacent the topthereof near the normal level of the recovered grease, oil or fattodirect 'said last named part of the incoming stream over said partitionand against the oil or greasecollected on the inlet side of thepartition Wall.

3. A separator for separating liquids of different specific gravities,adapted to function under continuous flow conditions, comprising a receptacle having an inlet branch and an outlet branch, a partition walldisposed' within the receptacle between the inlet and outlet endsthereof to divide.` the receptacle into two zones in one of whichturbulence ofthe inflowing liquid is created and in the other oi?` whichthe separated liquids are maintained relatively quiescent, saidpartition wall having an upward liquor ow re'- tarding edge disposedabove the lowermost part of the outlet, and battling means disposedadjacent the inlet opening of the receptacle serving to di-` waters andserving'to direct an auxiliary stream upwardly and horizontally `acrossthe top of the turbulencezone, the upper liquid retarding edge of saidbaiiie member being disposed above the lowermost part of the outlet.

, 4. A device of the character described including a receptacle having awater and grease or oil inlet, a draw-off opening for removing separatedoil or grease, amain outlet and an air-pressure relief opening formed inthe receptacle to` extendl into the 'main outlet, the receptaclecomprising a liquid-separating means and said draw-off opening beingdisposed above the pressure relief opening and the level of the waterwithin the receptacle which is below the separated grease or oil,whereby grease or oil may only be withdrawn when a sufficient quantityof the same has accumulated above the water level.

5. A device'of the character described includ ing a receptacle having awater and grease or oil inlet and adjustable means having a draw-offopening for removing separated oil or grease, a main outlet and anair-pressure relief opening formed in the receptacle, the receptaclecomprising a liquid-separating means. said draw-off opening beingdisposed above the pressure-relief opening and the level of the waterwithin the receptacle which is below ,the separated grease or oil andthe opening being formed in the adjustable means adapted to be adjustedto vary the elevation of said opening relative to the main outlet level,whereby grease or oil may only be withdrawn when a suflicient quantityof the same has i accumulated above the water level. i JOSEPHHIRSHSTEIIN.,

